Better gas mileage

I post this because there's alot of posts with Gen II's with mystery poor mileage. This may help:

Just recently the mpg's tanked in my 07. I presently have 36,000 miles on the car and its very well maintained. I bought the car new so i know it very well. I know alot about the car and checked all the usual suspects but everything was ok.
NO cel's either. Ran fine...no real extended engine run on & T battery charging perfectly too. The aux battery is not perfect but still is pretty good. I have never heard the traction battery fan come on. Just really poor mileage.

I did notice upon careful inspection that the flow through the Inverter coolant tank was no where's as close as it used to be. I know exactly how turbulent it should look. It now looked hardly bubbly at all. Hardly any movement. Is my pump dying?
I double checked the Coolant PUMP TSB website against my VIN and I am not a coolant replacement candidate.

I took the car to the dealer to discuss this. Especially the weak turbulence. Hoping I could squeeze a pump under warranty out of them. All I could get to look at my coolant tank was the Service Manager and I think you can guess what he said. Lots of shrugs and oh wells. Let us do a thorough check. If it needs a pump we'll do it under warranty.

Long story shrt no pump needed as it did have flow and the tech came out and said he hooked the Techstream to it and took it for a ride and got 40 mpg's.
$100 diag fee later I'm rolling out of the dealer and wow my mfd when I got in now say's 29 mpg's. It said 30 when I brought the car in.

When they gave me the bads news that my car was fine I went into the part depts and bought a gallon of SLLC. No way are they drilling me another $100 to change the Inv coolant.

I thought first place to go is change the Inv coolant. I did not like the way it looked anyway. Very cloudy. Lots of aluminum salts on the cap too that I remove once in a while and still see it.
If that didn't do it I was going to do the pump on my own nickle because something was not right.

Using PATRICKS great post about how to change the coolant it was easy. Took 20 minutes and hardly any tools at all just the big socket to dump the coolant at the cvt. I flushed it out, new coolant and bled it using the bleeder valve. Easy.

I was rewarded by new very aggressive turbulence in the reservoir.
Very obvious turbulance now. Great!
I thought thats awesome but lets see how the mpg's do.
I filled it up and reset the mfd and took it too work the next day. For the first time I got 56 mpg's on my commute. Never saw that before. It has averaged out to 49-50 on my commute ever since which is better than I have had in years.

So if your car is more than 3 years old and still has the original Inverter coolant its worth it to replace it. There is some aluminum corrosion going on there via the Inverter cooling section and its hard on the coolant. It may make the coolant very abrasive or contaminated which lessens its ability to absorb heat quickly enough. It looked very cloudy.
Apparently the pump struggles with proper flow if the coolant is not in good condition. And that really hurts mileage as the Inverter and trans is not being cooled efficiently.

 

Thanks I fixed it. It was SLLC.

 

Yeah the deal I made was there "Hybrid tech" would inspect it and if flow/turbulence was not up to par they would replace the pump
under warranty. If not it would be a $100 diag fee. I felt fairly certain that the HT would plainly see the anemic turbulence so I rolled the dice.
The HT said it appeared fine. Glanced at it I guess.
To me it was not even close to where it was when new. I guess as a tech you either have to actually own the car from new or be very very experienced in the minutiae of these cars with things like this. I lossed the toss. But won the battle because the car is running
perfect again.
If your not your own advocate with these cars the dealer will blow you off and jerk you around all at $100 an hour. Its a tough car to own after it gets older and starts having minor issues if your not a good mechanic or engineer. The dealer will just take you home.
Because even a minor malady will impact mileage.

Case in point as they were laying the bill on me and could plainly see I was not happy they still rolled out the 35K service plan board with the throttle body cleaning and the brake fluid analysis and replacement, hybrid system checks, ceiling wax, and christ on and on all for the good, better, best $99 each.
They could hit you for $500 easy for nothing.
I just said your kidding right? ....and they slinked away.

I hate car dealerships.

 

I searched for Pats post but cannot locate it. Lots of other posts about it though and a bunch of You Tubes about it too.
Maybe Pat can weigh in and post it again.

Its really easy with the built in bleeder valve. All you need is a gallon of SLLC a few tools and a good set of ears.
I'll probably do it once once a year now that I know how to do it.

 

No air bubbles and pump was not loud at all pre change.
Coolant was very cloudy when removed. Definite aluminum corrosion imho. Maybe its time...or heat.
Pump seems more quiet now.

But I can say dramatic mileage improvement since changed. I had an Fluke 62 Hand held IR Thermometer but was loaned out and now lost.
I wish I could have done a before & after temp test on the Inverter & trans.
I can say by feel the Inverter was getting pretty hot.
Now it seems to be much cooler. The Inverter hardly gets hot at all during normal use. I did tests a while back and it never got above 110 degree's even in Florida stop & go but the second you park it it heats soaks real quick and shoots up to + 130.

I'll have to buy another 62.